selftests/bpf: Allow substituting custom vmlinux.h for selftests build

Similarly to bpftool Makefile, allow to specify custom location of vmlinux.h
to be used during the build. This allows simpler testing setups with
checked-in pre-generated vmlinux.h.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200630004759.521530-2-andriin@fb.com

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 22aaec74ea0ab50ba5b6a01f4db4e838f60f02cd..1f9c696b3edf45f33ec024b90144fa07202df263 100644 (file)
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -134,12 +134,12 @@ $(OUTPUT)/test_stub.o: test_stub.c $(BPFOBJ)
        $(call msg,CC,,$@)
        $(CC) -c $(CFLAGS) -o $@ $<
 
-VMLINUX_BTF_PATHS := $(if $(O),$(O)/vmlinux)                           \
+VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)                           \
                     $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux)    \
                     ../../../../vmlinux                                \
                     /sys/kernel/btf/vmlinux                            \
                     /boot/vmlinux-$(shell uname -r)
-VMLINUX_BTF := $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
+VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
 
 $(OUTPUT)/runqslower: $(BPFOBJ)
        $(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/runqslower     \
@@ -182,8 +182,13 @@ $(BUILD_DIR)/libbpf $(BUILD_DIR)/bpftool $(INCLUDE_DIR):
        mkdir -p $@
 
 $(INCLUDE_DIR)/vmlinux.h: $(VMLINUX_BTF) | $(BPFTOOL) $(INCLUDE_DIR)
+ifeq ($(VMLINUX_H),)
        $(call msg,GEN,,$@)
        $(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
+else
+       $(call msg,CP,,$@)
+       cp "$(VMLINUX_H)" $@
+endif
 
 # Get Clang's default includes on this system, as opposed to those seen by
 # '-target bpf'. This fixes "missing" files on some architectures/distros,